The present invention relates to the field of combustion detection for an internal combustion engine.
More precisely, the invention relates, according to a first of its subjects, to a method for processing a pressure signal (p) originating from a pressure sensor mounted in a combustion chamber, for the purpose of detecting combustion in an internal combustion engine, comprising the steps consisting in:                supplying a pressure signal (p),        filtering the pressure signal (p) by filtering means having a variable gain (7),        establishing an output signal (out) representative of the filtered pressure signal (p), and        establishing a signal (e) representative of the error between the pressure signal (p) and the output signal (out).        
Such a method is known to those skilled in the art.
However, the various solutions proposed by the prior art in order to modify the bandwidth of the means for filtering the pressure signal lead to nonlinear filters.
In addition, these solution are based on the hypothesis that combustion takes place during the compression phase of the cylinder in the combustion chamber.
In certain cases, combustion may take place in the expansion phase of the thermodynamic cycle, in particular during combustions called exotic combustions. These combustions pose engine-control problems.